[Facial hemispasm and anomalies of the terminal portion of the vertebral artery (author's transl)].

A revision is suggested of the concept of "essential hemifacial spasm": 23 cases have been studied in whom the facial spasm was the only symptom present, while in 8 other cases in addition to the spasm of facial muscles other symptoms were noticed suggesting a pathology of the ponto-cerebellar angle. In many cases the symptom "spasm" and other concomitant symptoms are a direct consequence of an irritation due to compression on the nerve root (and/or on other nervous structures) owing to stretch of the distal tract of the vertebral artery or of the initial segment of the basilar artery. In five cases the AA. studied the vertebro-basilar circulation and in four patients they have actually found pathological elongations of the great vessels. In 18 other cases it was only possible to assume the presence of analogous alterations. The AA. suggest a study of the vertebro-basilar circulation in all the patients with "essential hemifacial spasm".